The present invention relates, in general, to semiconductor processing techniques, and more particularly, to a novel method of cleaning semiconductor wafers.
During the various processing steps required to transform a semiconductor wafer into semiconductor devices, process by-products and other contaminants often are left on the semiconductor wafer and in recesses, such as trenches, that have been formed in the wafer. In the past, a variety of chemical, mechanical, and combined chemical-mechanical methods (such as ultrasonic and megasonic cleaning) have been employed to remove these contaminants. The contaminants often are a combination of materials including organic materials resulting from photoresist resins, fluoro-polymers that result from fluorine plasma etching operations, and inorganic materials including silicon particles.
Previous wafer cleaning methods typically can not remove such combinations of materials. Chemical cleaning methods generally can remove either organic materials or inorganic materials, but not both. Combined chemical-mechanical cleaning methods do not overcome these deficiencies. In addition, combined chemical-mechanical methods generally are not capable of removing small particles, less than one-half micron, that settle into the wafer's small recesses.
Accordingly, it is desirable to have a method of cleaning semiconductor wafers that can remove both organic and inorganic contaminants, that can remove small (less than one-half micron) contaminants, and that can remove contaminants from the wafer's small recesses.